The Nitrous Oxide thread
So you wanna step with the big boys? whether its a 4 cylinder festive or a huge 572 chevy Nitrous Oxide can add a great bump in power. some kits can be as low as 25 horsepower while some go up to 400 HP. well If your just curious or need help with installation this is the thread for you.
So lets learn a little about how Nitrous works.
Liquid Nitrous Oxide along with some additional enrichment fuel is injected into the induction system "somewhere" along its length. Where exactly that position is, isn't important, provided that it goes into the engine evenly, with the same amount of Nitrous Oxide and additional fuel to each cylinder. That's all that's important here -- that it gets into the engines intake where it is carried to the combustion chamber.
So yeah hows it make power you ask?
Torque is the force that turns the crankshaft and creates acceleration. People are consumed with hp numbers, but hp is not what creates acceleration for winning drag races. Hp does create top end speed which is fine for land speed records or long distance endurance racing where acceleration rate / torque is not what determines the winner. To get the best out of nitrous, you need to utilize the massive torque it provides and concentrate on getting the highest torque across the whole rpm range.
Nitrous oxide systems make large amounts of torque by allowing an engine to burn more fuel at a lower rpm range than normal. Burning more fuel this way creates a longer burn period (and slightly higher cylinder pressures, if the timing is not corrected), that will push down on the pistons with greater average force. When the nitrous is injected into an engine and the initial combustion takes place, it creates enough heat to separate the nitrous oxide into its two components, nitrogen and oxygen. Once separated, the additional oxygen is then free to allow combustion of the additional fuel, while the released nitrogen acts as a buffer against detonation and damps mechanical loads.
To run nitrous successfully and safely, you have to introduce precise amounts of additional fuel with precise amounts of nitrous oxide. All of the extra oxygen provided by the nitrous oxide must have fuel with which to burn or you may damage your engine severely. When the amount of nitrous and the amount of supplemental fuel is controlled precisely, your engine can safely and reliably generate exceptional power increases.
Combustion : Nitrous oxide does not burn, it is an oxidiser. It provides more oxygen, so more fuel can be burned, and the result is more power. The atoms in a nitrous oxide molecule are bonded together. The oxygen is not free, but fortunately the bond breaks down as temperature rises. At 565° F, the bond is broken and the oxygen is then free. Combustion temperatures are much more than 565°, so it's not a problem. By adding nitrous oxide to an engine, the total amount of oxygen is increased while the volume of nitrogen is decreased (as a percentage of the whole). This speeds the burn rate and requires less timing advance for peak output. It is hard for many people to grasp gaining power with less timing, but it's a fact. Peak cylinder pressure must occur at approximately 20°ATDC to make peak power. If you speed the burn rate, peak cylinder pressure will occur too soon. It is easy to run too much ignition advance with nitrous, but too much will not only hurt power, it can quickly bring a nitrous engine into detonation and destroy it.
Detonation : Large power increases achieved by using nitrous oxide can increase the chance of detonation. To keep the engine out of detonation, you must control the extra heat that nitrous can make. The easiest way to do this is to add more fuel. All nitrous systems come with rich jetting to give you a safe starting point. The extra fuel takes away heat and raises the detonation limit. If you don't try to over do it, and keep the hp levels within reason, running slightly richer should be all you'll need to control detonation. Running richer will reduce the power output, but raising the detonation limit will allow more nitrous to be used to get more power.
Nitrous-to-fuel Ratios : The chemically correct nitrous to petrol ratio is 9.649:1. If a nitrous engine runs lean, it can destroy the engine in a matter of seconds. There must be enough fuel to maintain this correct ratio, if there isn't, temperatures rise rapidly. The oxygen that was left over from burning the limited amount of fuel will result is a lean burn situation raising cylinder temperatures and melting components. So don't run lean.
Cooling Effects : Cooler intake air is denser and contains more oxygen atoms per cubic foot. So cooler air will allow more fuel to be burned and in turn, make more power. A 10 degree drop in temperature can add 1 to 1.5% power to an engine. Nitrous oxide boils at -129°F and it will begin to boil as soon as it is injected. This can cause an 80° or so drop in manifold air temperature. Now if we are dealing with say a 400 hp engine, we can see a gain of well over 30 hp from the cooling effect alone. This cooling effect also helps the engine deal with detonation.
So lets learn a little about how Nitrous works.
Liquid Nitrous Oxide along with some additional enrichment fuel is injected into the induction system "somewhere" along its length. Where exactly that position is, isn't important, provided that it goes into the engine evenly, with the same amount of Nitrous Oxide and additional fuel to each cylinder. That's all that's important here -- that it gets into the engines intake where it is carried to the combustion chamber.
So yeah hows it make power you ask?
Torque is the force that turns the crankshaft and creates acceleration. People are consumed with hp numbers, but hp is not what creates acceleration for winning drag races. Hp does create top end speed which is fine for land speed records or long distance endurance racing where acceleration rate / torque is not what determines the winner. To get the best out of nitrous, you need to utilize the massive torque it provides and concentrate on getting the highest torque across the whole rpm range.
Nitrous oxide systems make large amounts of torque by allowing an engine to burn more fuel at a lower rpm range than normal. Burning more fuel this way creates a longer burn period (and slightly higher cylinder pressures, if the timing is not corrected), that will push down on the pistons with greater average force. When the nitrous is injected into an engine and the initial combustion takes place, it creates enough heat to separate the nitrous oxide into its two components, nitrogen and oxygen. Once separated, the additional oxygen is then free to allow combustion of the additional fuel, while the released nitrogen acts as a buffer against detonation and damps mechanical loads.
To run nitrous successfully and safely, you have to introduce precise amounts of additional fuel with precise amounts of nitrous oxide. All of the extra oxygen provided by the nitrous oxide must have fuel with which to burn or you may damage your engine severely. When the amount of nitrous and the amount of supplemental fuel is controlled precisely, your engine can safely and reliably generate exceptional power increases.
Combustion : Nitrous oxide does not burn, it is an oxidiser. It provides more oxygen, so more fuel can be burned, and the result is more power. The atoms in a nitrous oxide molecule are bonded together. The oxygen is not free, but fortunately the bond breaks down as temperature rises. At 565° F, the bond is broken and the oxygen is then free. Combustion temperatures are much more than 565°, so it's not a problem. By adding nitrous oxide to an engine, the total amount of oxygen is increased while the volume of nitrogen is decreased (as a percentage of the whole). This speeds the burn rate and requires less timing advance for peak output. It is hard for many people to grasp gaining power with less timing, but it's a fact. Peak cylinder pressure must occur at approximately 20°ATDC to make peak power. If you speed the burn rate, peak cylinder pressure will occur too soon. It is easy to run too much ignition advance with nitrous, but too much will not only hurt power, it can quickly bring a nitrous engine into detonation and destroy it.
Detonation : Large power increases achieved by using nitrous oxide can increase the chance of detonation. To keep the engine out of detonation, you must control the extra heat that nitrous can make. The easiest way to do this is to add more fuel. All nitrous systems come with rich jetting to give you a safe starting point. The extra fuel takes away heat and raises the detonation limit. If you don't try to over do it, and keep the hp levels within reason, running slightly richer should be all you'll need to control detonation. Running richer will reduce the power output, but raising the detonation limit will allow more nitrous to be used to get more power.
Nitrous-to-fuel Ratios : The chemically correct nitrous to petrol ratio is 9.649:1. If a nitrous engine runs lean, it can destroy the engine in a matter of seconds. There must be enough fuel to maintain this correct ratio, if there isn't, temperatures rise rapidly. The oxygen that was left over from burning the limited amount of fuel will result is a lean burn situation raising cylinder temperatures and melting components. So don't run lean.
Cooling Effects : Cooler intake air is denser and contains more oxygen atoms per cubic foot. So cooler air will allow more fuel to be burned and in turn, make more power. A 10 degree drop in temperature can add 1 to 1.5% power to an engine. Nitrous oxide boils at -129°F and it will begin to boil as soon as it is injected. This can cause an 80° or so drop in manifold air temperature. Now if we are dealing with say a 400 hp engine, we can see a gain of well over 30 hp from the cooling effect alone. This cooling effect also helps the engine deal with detonation.
Comments
Incorrect nitrous installations can be hazardous. With the bottle rolling around in the back seat, a careless driver not only risks injury by flying bottles in an accident, but also inconsistent nitrous flow. Most bottles have a pickup tube within them, which must be oriented so that it is always immersed in liquid nitrous. If the liquid is pulled away from it under acceleration or cornering, you get vapor and this causes a rich condition, resulting in a loss of power. Be sure to mount the bottle with bottle brackets and the pickup tube oriented correctly.
For systems that utilize a nozzle located in the air intake, location and orientation of the nozzle must be carefully selected, aiming the stream of nitrous into the throttle body without obstruction. It is also imperative that the point of injection be located downstream of the mass airflow sensor, if a vehicle is so equipped. The nitrous/fuel mixture can damage the sensor's tiny filament quite easily. In addition, nitrous blowing through it throws off the sensor's reading. Remember, one of the reasons nitrous works so well as a bolt-on for late-model vehicles is because the computer does not know it is there.
As another word of warning, don't forget to use nitrous filters and fuel filters. You do not want a nitrous solenoid to get stuck open on you because it gets dirty or worn out. Solenoids must also be rebuilt periodically, but it takes a lot of use to wear them out.
Unless you are using a progressive system, nitrous oxide may only be used under full-throttle conditions at sufficient engine speeds, 2500 rpm being the suggested minimum. Failure to comply with this rule can result in a very damaging situation, the most awesome being the infamous nitrous backfire. This event can easily blow apart your intake system, cause cosmetic damage, and start a fire. To prevent this, install a full-throttle activation switch. This switch needs to be mounted so that some part of the throttle body mechanism contacts it at full throttle, allowing the system to operate. It's also a good idea to have an rpm-activated switch so that the system can't operate below a certain engine speed, 2500 being the minimum.
It's good practice to rid the nitrous lines of vapor, in order to avoid a rich condition and hesitation upon system activation. However, many people do this by simultaneously whacking the throttle and hitting the nitrous while in neutral. Occasionally this results in the aforementioned violent intake explosion. It is therefore in your best interest to have a purge solenoid kit, which at the simple press of a button vents nitrous into the atmosphere. The purge line should be mounted where visible, so that one can watch for when the plume of gas blows thick and stable, indicating that liquid has reached the solenoids and the system is ready to go.
Bottle Pressure
Bottle pressure is a function of both the amount of nitrous remaining in the bottle and the temperature of the bottle. On a cold day you may only see 600 psi, while on an extremely hot day you could see well over 1,000 psi. Because the flow rate of the nitrous is greatly affected by pressure, it's important to run the same pressure every time. An electric bottle warmer is the solution to this. Most bottle warmers are equipped with thermostats that automatically turn the warmer on and off to keep the bottle within a certain temperature range. Unfortunately, due to their simple design, such thermostats are highly unreliable. Eliminate the thermostat and rely only on a manual switch to operate the warmer.
Generally, nitrous flows well anywhere from 800 psi up. A pressure of about 1,050 psi is a good choice because this is what the pressure will be anyway on a warm summer day, so you'll never have to cool the bottle. Install a nitrous pressure gauge on the dashboard where you can quickly reference it, and have the switch for the bottle warmer right there as well. This way, you can turn the warmer on and off and keep pressure at its optimum. Just remember to watch bottle pressure closely and not leave the warmer on while unattended.
Exhaust Gas Pyrometers
The temperature of an engine's exhaust gases is related to several factors, including the amount of power being made, the air/fuel ratio of your intake charge, and ignition timing. For our interests, higher exhaust temperatures are the result of leaner mixtures, while lower exhaust gas temperatures indicate overly rich mixtures.
Ignition System
In order to ignite that potent intake charge, good aftermarket ignition systems along with reduced spark plug gaps are needed. A spec of 0.035 inches is a good number for spark plug gap. In addition, colder-heat-range spark plugs are normally necessary to dissipate heat from the plug, averting misfire and plug melting. Normally one or two heat ranges colder is sufficient. "Projected nose" plugs, which reach deep into the combustion chamber, also cause problems because heat can't leave them fast enough. And unfortunately, platinum plugs are not going to cut it either. Platinum is a poor conductor of both spark energy and heat, and this is exactly what you don't want.
Probably the most important thing to remember in terms of the ignition system is not to use too much timing advance. While it's true that when you advance timing, you make more power--until you get to the point of detonation--much less timing is needed to arrive at optimum power with nitrous use. Due to the much higher cylinder pressures generated by a more intense burn, nitrous motors need retarded ignition timing in order to delay the time of peak pressure, keeping cylinder pressures within reason and thus avoiding abnormal combustion.
In this case as well, it's best to follow the guidelines recommended by nitrous system manufacturers when it comes to amount of timing retard required. Often the stock setting is acceptable, but when not shooting the spray, most cars perform better with advanced timing. This doesn't mean that you need to run retarded timing all the time and lose performance when running naturally-aspirated. Companies like MSD Ignition offer a number of devices that allow you to retard timing as needed when the juice starts to flow. A retard unit will automatically retard timing by a user-defined amount whenever the system is turned on. This setup is simple and foolproof. Another device available for retarding timing is an adjustable timing control. This unit has a knob that allows you to adjust timing over a wide range from the comfort of your driver's seat. When you want to use some spray, just turn the knob back to the desired timing and off you go. The disadvantage to this approach is that you have to actually remember to twist the knob back when you are about to use the system. If you can trust yourself to remember this, you'll enjoy on-the-fly, instantaneous timing adjustments for tuning purposes and to compensate for different situations on the street (such as best fuel economy).
A related topic to ignition is an rpm limiter. Many factory limiters work by cutting fuel flow to prevent the engine from spinning faster. This is not what you want, because combining nitrous with spark without sufficient fuel spells trouble. Make sure your limiter works by cutting spark, not fuel. Almost all aftermarket units function in this way.
That's right, it's time for a trip to the local drag strip, and you may very well surprise yourself at how well you can get your system to work for you. Even if your car is only used for street operation, the track provides the only real measurement of whether changes in your system have done any good. Seat-of-the-pants feel is too subjective a judgment, but the timing lights at the drags will let the facts be known.
The car must first be tuned for maximum performance in naturally-aspirated form to provide a baseline starting point. Once this is accomplished you can begin trying out the nitrous, starting out with the jetting recommended by the manufacturer for your chosen power level. First, you'll have to experiment with launch tactics. If you can't hit the juice immediately, you'll have to plan on flicking the switch a few moments after the launch. Here, having an rpm-activated switch or time delay switch can really come in handy, as you can set it so the system does this for you, taking away a lot of human error and making for very consistent passes.
Now the tuning begins. Make a couple initial passes, noting the EGT reading after you pass the quarter-mile mark. If it isn't near 1,350*, step down to a leaner (smaller number) fuel jet. Make some more passes, always keeping an eye on EGTs, and seeing if the trap speed has increased. Trap speed is a far better indicator of performance because it is less affected by traction and user error (such as switch flicking) than elapsed time. If you achieve higher trap speed and EGTs aren't too high, go leaner still. Continue this process of re-jetting and making passes until either you don't gain anything or the EGTs get too high. At this point, put back in the next richer jet, just to be safe, and you have your best mixture.
When you get home, a spark plug check is in order. Nitrous has the characteristic of cleaning plugs to make them appear like new, so the traditional method of "reading" the plugs doesn't always work. Any evidence of melting means that you are a bit too lean or you need a higher octane fuel, or that the plug heat range is too hot. An overly dirty or fouled plug would indicate too cold a heat range, an insufficient ignition system, or some other ignition problem. After correcting any problems and using the nitrous a few more times, check the plugs again to make sure all is well. Get used to this process, because you'll be changing the spark plugs more often. Any high horsepower machine will eat up spark plugs more quickly, and nitrous can do a number on them.
On subsequent trips to the track, in addition to fine-tuning the mixture, you might try adjusting the engine speed at which you change gears. It turns out that because nitrous makes such an incredible amount of torque all over the power band, a motor on nitrous assistance does not need to be revved as high and many people have discovered that the motor will perform better if it is "lugged." Also, realize that changes in outside air temperature will affect the air/fuel mixture just like a naturally-aspirated car, so you'll probably have to run fatter jetting in colder weather.
Conclusion
So as you can see there is more to using nitrous oxide than simply throwing a kit on and hitting the button. When you take the time to do things right, tuning and maintaining your system, you'll enjoy safe, trouble-free operation, all while making power that is even further beyond the ordinary. Good luck and keep the shiny side up.